The present invention concerns the control of a multiplex connection unit in a time-division switching exchange.
As is well known, a time-division switching exchange is connected to electromechanical exchanges, to time-division exchanges or to remote concentrators known as "satellite" exchanges. Each exchange has its own, so-called "remote" clock, which is slightly out of synchronization with the local clock. The multiplex time slots must therefore be synchronised with the local clock before it is possible to detect a frame alignment word and a multiframe alignment word so as to be able to extract the signal sent in each frame by each multiplex line.
Multiplex connection units are described in the article by Feuerstein, Jacob, Renoulin and Guezou under the title "Groupe d'Equipements de synchronisation du systeme de commutation temporelle Platon", in the journal "Commutation et Electronique" No. 34, July 1971, pages 7 to 24.
These multiplex connection units are controlled by logic systems described by Jacob, Renoulin and Voyer in "Concentrateur spatio-temporel 500 abonnes pour systeme de commutation temporelle Platon E10" in the journal "Commutation et Electronique", No. 34, July 1971, pages 25 to 47.
The French patent application filed on the same date as the present application by the same applicants under the title "Dispositif de raccordement de multiplex dans un central de commutation temporelle" ("Multiplex connection device for time-division exchanges"), corresponding to copending U.S. Pat. application Ser. No. 146,985, filed May 5, 1980, describes a modular multiplex connection unit controlled by a logic system of the type described in the aforementioned article.
The control logic systems of known connection devices have the disadvantage that they are not able to control more than four connection modules, imposing constraints on exchange location since a large number of control logic circuits are required for all the multiplex lines to be synchronised.